Cannot export to FBX file, does anyone know how to fix this?
I think your problem may be an invalid UVW map. Here is the developer task associated with this error. You can try two things:
Run the following code in Blender before exporting until the bug is fixed (Credit  Michael Campbell):

import bpy

for ob in bpy.data.objects:
    if not ob.type =='MESH':
        print(ob.name,'is not a mesh, skipping\n')
        continue
    print(ob.name,'\n')
    m = ob.data
    if m.validate(verbose=True):
        print(&quot;something was fixed with the mesh&quot;)
    else:
        print(&quot;mesh was fine&quot;)
        
    print(&quot; and the cached custom data has been cleared to avoid export issues&quot;)

If this doesn't work, try clearing and recreating the UV map. Make sure everything is unwrapped properly.
Another thing to check is to make sure all of your objects have correct location and scale values. Some people have reported export problems where certain objects somehow got set to NaN (Not a number) and weird scaling values.
As a last resort, I would try deleting everything from your scene one by one and try exporting to FBX after each and every deletion. This may help you narrow things down and isolate the culprit of the crash.